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Abstract:
We use the complete Bouguer anomaly (CBA) derived from GGMplus 2013 to model the lithosphere–asthenosphere boundary (LAB) depth, LAB temperature, lithospheric mantle density and crustal/lithospheric mantle structure of the central main Ethiopian rift (CMER) and surrounding regions. The regional Bouguer anomaly is estimated by using a 200-km cutoff wavelength low-pass filter, and the resulting anomaly map is inverted using Parker–Oldenburg method to generate the depth to the LAB. The result shows that the LAB depth values fluctuate between 38.8 and 78 km in the region. The LAB temperature is estimated based on the results of the LAB depth in the CMER and surrounding regions. The LAB temperature estimates range between 1267 and 1287 °C in the region. The lithospheric mantle density in the study area varies from 3240 to 3295 kg/m3, as estimated using empirical equations. Relatively low lithospheric mantle densities are determined to occur beneath the Yerer-Tullu-Wellel Volcanotectonic Lineament and Boru-Toru Structural High. 3D gravity models computed for the study area show thickening of the bottom interfaces of the top layer, upper and lower crystalline basement depths when going from the rift toward the western and eastern plateaus. This crustal thickening is evidenced by the associated low CBA (approximately − 285 mGal) observed over the plateaus.
